Universe Guide

Pi Mensae

Pi Mensae Facts

  • Pi Mensae is a subgiant star that can be located in the constellation of Mensa. The description is based on the spectral class.
  • Pi Mensae is not part of the constellation outline but is within the borders of the constellation.
  • Based on the spectral type (G3IV) of the star, the star's colour is yellow .
  • The star can be seen with the naked eye, that is, you don't need a telescope/binoculars to see it.
  • The star has an estimated age of 3.50 Billion of Years but could be as young as 0.50 to 5.50 according to Hipparcos.
  • Pi Mensae has at least 1 Extrasolar Planets believed to be in orbit around the star.
  • Using the most recent figures given by the 2007 Hipparcos data, the star is 59.74 light years away from us. Distance

Information on Pi Mensae

Pi Mensae was known to have an exoplanet in orbit round the star for a while but N.A.S.A.'s TESS exoplanet hunter spotted a second exoplanet in orbit round the star. It was one of the first exoplanets to be discovered and revealed by the N.A.S.A. team.

Pi Mensae's Alternative Names

Pi Mensae (Pi. Men) is the Bayer Classification for the star. The Bayer Classification was created by Johann Bayer in 1603. The brightest star in the constellation is normally given the Alpha designation, there are exceptions such as Pollux which is Beta Geminorum.

The Id of the star in the Yale Bright Star Catalogue is HR2022. HIP26394 is the reference name for the star in the Hipparcos Star Catalogue. The Id of the star in the Henry Draper catalogue is HD39091.

More details on objects' alternative names can be found at Star Names .

Location of Pi Mensae

The location of the subgiant star in the night sky is determined by the Right Ascension (R.A.) and Declination (Dec.), these are equivalent to the Longitude and Latitude on the Earth. The Right Ascension is how far expressed in time (hh:mm:ss) the star is along the celestial equator. If the R.A. is positive then its eastwards. The Declination is how far north or south the object is compared to the celestial equator and is expressed in degrees. For Pi Mensae, the location is 05h 37m 08.79 and -80° 28` 18.0 .

Radial Velocity and Proper Motion of Pi Mensae

Proper Motion

All stars like planets orbit round a central spot, in the case of planets, its the central star such as the Sun. In the case of a star, its the galactic centre. The constellations that we see today will be different than they were 50,000 years ago or 50,000 years from now. Proper Motion details the movements of these stars and are measured in milliarcseconds. The star is moving 1,050.38 ± 0.20 milliarcseconds/year towards the north and 312.01 ± 0.21 milliarcseconds/year east if we saw them in the horizon.

Radial Velocity

The Radial Velocity, that is the speed at which the star is moving away/towards the Sun is 10.90000 km/s with an error of about 0.74 km/s . When the value is negative then the star and the Sun are getting closer to one another, likewise, a positive number means that two stars are moving away. Its nothing to fear as the stars are so far apart, they won't collide in our life-time, if ever.

Physical Properties of Pi Mensae

Pi Mensae Temperature and Colour

Based on the star's spectral type of G3IV , Pi Mensae's colour and type is yellow subgiant star. The star's effective temperature is 5,950 Kelvin which is hotter than our own Sun's effective Temperature which is 5,777 Kelvin.

Pi Mensae Luminosity

Luminosity is the amount of energy that a star pumps out and its relative to the amount that our star, the Sun gives out. The figure of 1.67 that I have given is based on the value in the Simbad Hipparcos Extended Catalogue at the University of Strasbourg from 2012.

Pi Mensae Radius

Pi Mensae estimated radius has been calculated as being 1.21 times bigger than the Sun. The Sun's radius is 695,800km, therefore the star's radius is an estimated 840,189.99.km. If you need the diameter of the star, you just need to multiple the radius by 2. However with the 2007 release of updated Hipparcos files, the radius is now calculated at being round 1.2130904362482041543893752750. The figure is derived at by using the formula from SDSS rather than peer reviewed papers. It has been known to produce widely incorrect figures.

Pi Mensae Mass

The Pi Mensae's solar mass is 1.10 times that of our star, the Sun. The Sun's Mass is 1,989,100,000,000,000,000,000 billion kg. which to calculate using this website is too large. To give idea of size, the Sun is 99.86% the mass of the solar system.

Pi Mensae Metalicity

The star's metallicity is 0.090000, this value is the fractional amount of the star that is not Hydrogen (X) or Helium (Y). An older star would have a high metallicity whereas a new star would have a lower one.

Pi Mensae Estimated Age

The stars age according to Hipparcos data files put the star at an age of about 3.50 Billion years old but could be between 0.50 and 5.50 Billion years old. In comparison, the Sun's age is about 4.6 Billion Years Old.

Pi Mensae Apparent and Absolute Magnitudes

Pi Mensae has an apparent magnitude of 5.65 which is how bright we see the star from Earth. Apparent Magnitude is also known as Visual Magnitude. If you used the 1997 Parallax value, you would get an absolute magnitude of 4.35 If you used the 2007 Parallax value, you would get an absolute magnitude of 4.34. Magnitude, whether it be apparent/visual or absolute magnitude is measured by a number, the smaller the number, the brighter the Star is. Our own Sun is the brightest star and therefore has the lowest of all magnitudes, -26.74. A faint star will have a high number.

Distance to Pi Mensae

Using the original Hipparcos data that was released in 1997, the parallax to the star was given as 54.92000 which gave the calculated distance to Pi Mensae as 59.39 light years away from Earth or 18.21 parsecs. If you want that in miles, it is about 349,131,560,913,374.60, based on 1 Ly = 5,878,625,373,183.61 miles.

In 2007, Hipparcos data was revised with a new parallax of 54.60000 which put Pi Mensae at a distance of 59.74 light years or 18.32 parsecs. It should not be taken as though the star is moving closer or further away from us. It is purely that the distance was recalculated.

Using the 2007 distance, the star is roughly 3,778,744.92 Astronomical Units from the Earth/Sun give or take a few. An Astronomical Unit is the distance between Earth and the Sun. The number of A.U. is the number of times that the star is from the Earth compared to the Sun. The star's Galacto-Centric Distance is 7,394.00 Parsecs or 24,116.52 Light Years. The Galacto-Centric Distance is the distance from the star to the Centre of the Galaxy which is Sagittarius A*.

Travel Time to Pi Mensae

The time it will take to travel to this star is dependent on how fast you are going. U.G. has done some calculations as to how long it will take going at differing speeds. A note about the calculations, when I'm talking about years, I'm talking non-leap years only (365 days).

The New Horizons space probe is the fastest probe that we've sent into space at the time of writing. Its primary mission was to visit Pluto which at the time of launch (2006), Pluto was still a planet.

DescriptionSpeed (m.p.h.)Time (years)
Airbus A38073654,432,931.27
Speed of Sound (Mach 1)767.26952,214,591.51
Concorde (Mach 2)1,534.5426,107,261.73
New Horizons Probe33,0001,214,019.32
Speed of Light670,616,629.0059.74

Source of Information

The source of the information if it has a Hip I.D. is from Simbad, the Hipparcos data library based at the University at Strasbourg, France. Hipparcos was a E.S.A. satellite operation launched in 1989 for four years. The items in red are values that I've calculated so they could well be wrong. Information regarding Metallicity and/or Mass is from the E.U. Exoplanets. The information was obtained as of 12th Feb 2017.

Hide Explanations
Show GridLines

Additional Pi Mensae Facts and Figures

Visual Facts

Primary / Proper / Traditional NamePi Mensae
Alternative NamesPi. Men, HD 39091, HIP 26394, HR 2022
Spectral TypeG3IV
Constellation's Main StarNo
Multiple Star SystemNo / Unknown
Star TypeSubgiant Star
GalaxyMilky Way
Age3.50 Billion Years Old
Age Range0.50 - 5.50 Billion Years Old
Absolute Magnitude 4.35 / 4.34
Visual / Apparent Magnitude5.65
Naked Eye VisibleYes - Magnitudes
Right Ascension (R.A.)05h 37m 08.79
Declination (Dec.)-80° 28` 18.0
Galactic Latitude-29.77645075 degrees
Galactic Longitude292.51655834 degrees
1997 Distance from Earth54.92000 Parallax (milliarcseconds)
 59.39 Light Years
 18.21 Parsecs
2007 Distance from Earth54.60000 Parallax (milliarcseconds)
 59.74 Light Years
 18.32 Parsecs
 3,778,744.92 Astronomical Units
Galacto-Centric Distance24,116.52 Light Years / 7,394.00 Parsecs
Proper Motion Dec.1050.38000 ± 0.20000 milliarcseconds/year
Proper Motion RA.312.01000 ± 0.21000 milliarcseconds/year
B-V Index0.6
Radial Velocity10.90000 ± 0.74 km/s
Iron Abundance0.0700 ± 0.01 Fe/H
Semi-Major Axis5751.0000000
Stellar Luminosity (Lsun)1.6700000

Companions (Multi-Star and Exoplanets) Facts

Exoplanet Count1

Estimated Calculated Facts

Radius (x the Sun)1.21
Effective Temperature5,895 Kelvin
Mass Compared to the Sun1.10

Sources and Links

SIMBAD SourceLink

Location of Pi Mensae in Mensa

Pi Mensae Location in Mensa

The map was generated using Night Vision, an awesome free application by Brian Simpson.

List of Extrasolar Planets orbiting Pi Mensae

NameStatusMass (Jupiters)Orbital Period (Days)EccentricityDiscoveredSemi-Major AxisPeriastronInclination
HD 39091 bConfirmed2049.0000.6120013.28330.000
Pi Mensae c6.26820180.0683987.270

Related Stars

Comments and Questions

There's no register feature and no need to give an email address if you don't need to. All messages will be reviewed before being displayed. Comments may be merged or altered slightly such as if an email address is given in the main body of the comment.

You can decline to give a name which if that is the case, the comment will be attributed to a random star. A name is preferred even if its a random made up one by yourself.

This website is using cookies. More info. That's Fine